Imperial College London

Dr Timothy Constandinou

Faculty of EngineeringDepartment of Electrical and Electronic Engineering

Reader in Neural Microsystems
 
 
 
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Contact

 

+44 (0)20 7594 0790t.constandinou Website

 
 
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Assistant

 

Miss Izabela Wojcicka-Grzesiak +44 (0)20 7594 0701

 
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Location

 

B407Bessemer BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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141 results found

Reverter F, Prodromakis T, Liu Y, Georgiou P, Nikolic K, Constandinou TGet al., 2014, Design Considerations for a CMOS Lab-on-Chip Microheater Array to Facilitate the in vitro Thermal Stimulation of Neurons, IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 630-633

CONFERENCE PAPER

Shepherd LM, Constandinou TG, Toumazou C, 2014, Towards ultra-low power bio-inspired processing, Body Sensor Networks, Publisher: Springer London, Pages: 273-299, ISBN: 9781447163732

The natural world is analogue and yet the modern microelectronic world with which we interact represents real world data using discrete quantities manipulated by logic. In the human space, we are entering a new wave of body-worn biosensor technology for medical diagnostics and therapy. This new trend is beginning to see the processing interface move back to using continuous quantities, which are more or less in line with the biological processes. We label this computational paradigm “bio-inspired” because of the ability of silicon chip technology which enables the use of inherent device physics, allowing us to approach the computational efficiencies of biology. From a conceptual viewpoint, this has led to a number of more specific morphologies including neuromorphic and retinomorphic processing. These have led scientists to model biological systems such as the cochlea and retina and gain not only superior computational resource efficiency (to conventional hearing aid or camera technology), but also an increased understanding of biological and neurological processes.

BOOK CHAPTER

Williams I, Constandinou TG, 2014, Computationally efficient modeling of proprioceptive signals in the upper limb for prostheses: a simulation study, FRONTIERS IN NEUROSCIENCE, Vol: 8, ISSN: 1662-453X

JOURNAL ARTICLE

Yang Y, Boling S, Eftekhar A, Paraskevopoulou SE, Constandinou TG, Mason AJet al., 2014, Computationally Efficient Feature Denoising Filter and Selection of Optimal Features for Noise Insensitive Spike Sorting, 36th Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society (EMBC), Publisher: IEEE, Pages: 1251-1254, ISSN: 1557-170X

CONFERENCE PAPER

Yoshizaki S, Serb A, Liu Y, Constandinou TGet al., 2014, Octagonal CMOS Image Sensor with Strobed RGB LED Illumination for Wireless Capsule Endoscopy, IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 1857-1860, ISSN: 0271-4302

CONFERENCE PAPER

Zheng L, Leene LB, Liu Y, Constandinou TGet al., 2014, An Adaptive 16/64 kHz, 9-bit SAR ADC with Peak-Aligned Sampling for Neural Spike Recording, IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 2385-2388, ISSN: 0271-4302

CONFERENCE PAPER

Barsakcioglu DY, Eftekhar A, Constandinou TG, 2013, Design Optimisation of Front-End Neural Interfaces for Spike Sorting Systems, IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 2501-2504, ISSN: 0271-4302

CONFERENCE PAPER

Koutsos E, Paraskevopoulou SE, Constandinou TG, 2013, A 1.5μW NEO-based Spike Detector with Adaptive-Threshold for Calibration-free Multichannel Neural Interfaces, IEEE International Symposium on Circuits and Systems (ISCAS)

This paper presents a novel front-end circuit for detecting action potentials in extracellular neural recordings. By implementing a real-time, adaptive algorithm to determine an effective threshold for robustly detecting a spike, the need for calibration and/or external monitoring is eliminated. The input signal is first pre-processed by utilising a non-linear energy operator (NEO) to effectively boost the signal-to-noise ratio (SNR) of the spike feature of interest. The spike detection threshold is then determined by tracking the peak NEO response and applying a non-linear gain to realise an adaptive response to different spike amplitudes and background noise levels. The proposed algorithm and its implementation is shown to achieve both accurate and robust spike detection, by minimising falsely detected spikes and/or missed spikes. The system has been implemented in a commercially available 0.18μm technology requiring a total power consumption of 1.5μW from a 1.8V supply and occupying a compact footprint of only 0.03$\,$mm$^2$ silicon area. The proposed circuit is thus ideally suited for high-channel count, calibration-free, neural interfaces.

CONFERENCE PAPER

Leene LB, Liu Y, Constandinou TG, 2013, A Compact Recording Array for Neural Interfaces, IEEE Biomedical Circuits and Systems Conference (BioCAS), Publisher: IEEE, Pages: 97-100, ISSN: 2163-4025

CONFERENCE PAPER

Leene LB, Luan S, Constandinou TG, 2013, A 890fJ/bit UWB transmitter for SOC integration in high bit-rate transcutaneous bio-implants, IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 2271-2274, ISSN: 0271-4302

CONFERENCE PAPER

Paraskevopoulou SE, Barsakcioglu DY, Saberi MR, Eftekhar A, Constandinou TGet al., 2013, Feature extraction using first and second derivative extrema (FSDE) for real-time and hardware-efficient spike sorting, JOURNAL OF NEUROSCIENCE METHODS, Vol: 215, Pages: 29-37, ISSN: 0165-0270

JOURNAL ARTICLE

Williams I, Constandinou TG, 2013, An Energy-Efficient, Dynamic Voltage Scaling Neural Stimulator for a Proprioceptive Prosthesis, IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS, Vol: 7, Pages: 129-139, ISSN: 1932-4545

JOURNAL ARTICLE

Williams I, Constandinou TG, 2013, Modelling muscle spindle dynamics for a proprioceptive prosthesis, Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBS), Publisher: IEEE

Muscle spindles are found throughout our skeletalmuscle tissue and continuously provide us with a sense of our limbs position and motion (proprioception). This paper advances a model for generating artificial muscle spindle signalsfor a prosthetic limb, with the aim of one day providing amputees with a sense of feeling in their artificial limb. By utilising the Opensim biomechanical modelling package the relationship between a joints angle and the length of surrounding muscles is estimated for a prosthetic limb. This is then applied to the established Mileusnic model to determine the associated muscle spindle firing pattern. This complete system model is then reduced to allow for a computationallyefficient hardware implementation. This reduction is achieved with minimal impact on accuracy by selecting key monoarticular muscles and fitting equations to relate joint angle to muscle length. Parameter values fitting the Mileusnic modelto human spindles are then proposed and validated against previously published human neural recordings. Finally, a model for fusimotor signals is also proposed based on data previously recorded from reduced animal experiments.

CONFERENCE PAPER

Woods SP, Constandinou TG, 2013, Wireless Capsule Endoscope for Targeted Drug Delivery: Mechanics and Design Considerations, IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, Vol: 60, Pages: 945-953, ISSN: 0018-9294

JOURNAL ARTICLE

Constandinou TG, Hafliger P, 2012, Guest Editorial-Special Issue on Selected Papers From BioCAS 2011, IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS, Vol: 6, Pages: 401-402, ISSN: 1932-4545

JOURNAL ARTICLE

Guilvard A, Eftekhar A, Luan S, Toumazou C, Constandinou TGet al., 2012, A Fully-Programmable Neural Interface for Multi-Polar, Multi-Channel Stimulation Strategies, IEEE International Symposium on Circuits and Systems, Publisher: IEEE, Pages: 2235-2238, ISSN: 0271-4302

CONFERENCE PAPER

Haaheim B, Constandinou TG, 2012, A Sub-1μW, 16kHz Current-Mode SAR-ADC for Neural Spike Recording, International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, ISSN: 0271-4302

This paper presents an ultra-low-power 8-bit asynchronous current-mode (CM) successive approximation (SAR) analogue-to-digital converter (ADC) for single-neuron spike recording. The novel design exploits CM techniques to support operation at supply voltages down to 1.2V, consuming under500nA at 16kSamples/s. The design features easy scalability, and allows for a tuneable sampling frequency and dynamic range (DR). The circuit is designed in a commercially-available 0.18u mCMOS technology and occupies a chip area of 0.078 sq.mm. The system requires a single, post-fabrication current calibration supportedby on-chip circuitry to ensure robust operation through process and mismatch variations.

CONFERENCE PAPER

Luan S, Constandinou TG, 2012, A Novel Charge-Metering Method for Voltage Mode Neural Stimulation, IEEE International Symposium on Circuits and Systems, Publisher: IEEE, Pages: 2239-2242, ISSN: 0271-4302

CONFERENCE PAPER

Mirza KB, Luan S, Eftekhar A, Constandinou TGet al., 2012, Towards a Fully-Integrated Solution for Capacitor-based Neural Stimulation, IEEE International Symposium on Circuits and Systems, Publisher: IEEE, Pages: 2243-2246, ISSN: 0271-4302

CONFERENCE PAPER

Paraskevopoulou SE, Constandinou TG, 2012, An Ultra-Low-Power Front-end Neural Interface with Automatic Gain for Uncalibrated Monitoring, IEEE International Symposium on Circuits and Systems, Publisher: IEEE, Pages: 193-196, ISSN: 0271-4302

CONFERENCE PAPER

Williams I, Constandinou TG, 2012, An Energy-Efficient, Dynamic Voltage Scaling Neural Stimulator for a Proprioceptive Prosthesis, IEEE International Symposium on Circuits and Systems, Publisher: IEEE, Pages: 1091-1094, ISSN: 0271-4302

CONFERENCE PAPER

Abshire P, Bermak A, Berner R, Cauwenberghs G, Chen S, Christen JB, Constandinou TG, Culurciello E, Dandin M, Datta T, Delbrück T, Dudek P, Eftekhar A, Etienne-Cummings R, Indiveri G, Law MK, Linares-Barranco B, Tapson J, Tang W, Zhai Yet al., 2011, Confession session: Learning from others mistakes., Publisher: IEEE, Pages: 1149-1162

CONFERENCE PAPER

Georgiou J, Andreou AG, 2011, Guest Editorial—Special Issue on Selected Papers From BioCAS 2010, IEEE Transactions on Biomedical Circuits and Systems, Vol: 5, Pages: 401-402, ISSN: 1932-4545

JOURNAL ARTICLE

Georgiou P, Prodromakis T, Constandinou TG, Toumazou Cet al., 2011, Sensor Array for Measuring Neural Activity

A sensor system comprising a substrate and integrated onto the substrate an array (7) of sensor elements (1), each sensor element comprising one or more inductors (3), one or more electrochemical sensors (4), and one or more optical sensors (2). The system further comprising a controller configured in use to separately address each of the sensor elements (1) to drive the respective inductors and receive outputs of the respective sensors.

PATENT

Goh CZD, Georgiou P, Constandinou TG, Prodromakis T, Toumazou Cet al., 2011, A CMOS-Based ISFET Chemical Imager With Auto-Calibration Capability, IEEE SENSORS JOURNAL, Vol: 11, Pages: 3253-3260, ISSN: 1530-437X

JOURNAL ARTICLE

Goh ZDC, Georgiou P, Constandinou TG, Prodromakis T, Toumazou Cet al., 2011, A CMOS-based lab-on-chip array for combined magnetic manipulation and opto-chemical sensing, Pages: 1998-2001, ISSN: 0271-4310

This paper presents a CMOS-based lab-on-chip platform for combined magnetic manipulation and opto-chemical sensing. Within each pixel, a Programmable Gate (PG) ISFET chemical sensor is combined with an active pixel sensor, and is encompassed within an inductive coil. The integrated pixel is tesselated to form an 8×8 array. Fabricated in a commercially available 0.35μm CMOS technology, the system can be used for simultaneous optical imaging and pH sensing, and includes autocalibration mechanisms for eliminating sensor non-idealities. A spatiotemporal magnetic field pattern generator has also been embedded for micro-scale magnetic manipulation. Controlled via a MATLAB based graphical user interface, the system achieves real time data acquisition at 6fps, a pH sensitivity of 57mV/pH and demonstrates magnetic manipulation of micro-beads. © 2011 IEEE.

CONFERENCE PAPER

Hu Y, Liu Y, Constandinou TG, Toumazou Cet al., 2011, A 5s-Time-Constant Temperature-Stable Integrator for a Tuneable PID Controller in LOC Applications, IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 1387-1390, ISSN: 0271-4302

CONFERENCE PAPER

Liu Y, Georgiou P, Prodromakis T, Constandinou TG, Toumazou Cet al., 2011, An Extended CMOS ISFET Model Incorporating the Physical Design Geometry and the Effects on Performance and Offset Variation, IEEE TRANSACTIONS ON ELECTRON DEVICES, Vol: 58, Pages: 4414-4422, ISSN: 0018-9383

JOURNAL ARTICLE

Luan S, Eftekhar A, Murphy OH, Constandinou TGet al., 2011, Towards an Inductively Coupled Power/Data Link for Bondpad-less Silicon Chips, IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 2597-2600, ISSN: 0271-4302

CONFERENCE PAPER

Nikolic K, Constandinou TG, Toumazou C, 2011, Method and Apparatus for Optically Outputting Information from a Semiconductor Device

A method of optically outputting information (e.g. digital data) from a semiconductor device, the method comprising: providing a semiconductor device having a semiconducting p-n junction, the p-n junction having a region of reduced free charge carrier density; applying an electrical signal to modulate the extent of the said region, the electrical signal being representative of the information to be outputted; arranging incident light to pass through at least part of the said region, such that the light is at least partially absorbed in dependence upon the modulated extent of the said region, thereby producing intensity-modulated output light; and detecting the intensity of the output light and thereby determining the outputted information. Also provided is an electro-optical assembly, a package module for mounting a semiconductor device on a printed circuit board, and an integrated circuit chip.

PATENT

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